The present invention is achieved through the formation of images by employing a thermal transfer method such as sublimable thermal transfer method or the like. More particularly, the present invention relates to an image-printed material used as an electric-decorating display members as well as a thermal transfer sheet and a recording method used in producing the image-printed material.
Conventional electric-decorating display members are made, for example, by printing characters and images on films, such as plastic films through a method of offset printing or gravure printing with the use of a previously prepared form plate. When a clear film is used, white ink is solid-printed over a printed portion of the clear film, to form an electric-decorating display member. In these methods, characters and/or images formed on substrates should has the identical information for one printing lot.
In contrast, as can be seen in recent personal use, there has been strong needs that different characters and/or images can be printed at every time so as to vary the information on every electric-decorating display member. To meet such needs, the electric-decorating display member is formed by that, for the purpose of increasing absorption of water-color ink, a receptor layer containing fillers and high-absorbing resins is provided on a substrate made of hydrophobic substances such as plastic films, then the characters and/or images are recorded on the receptor layer through ink jet printing. Thus recorded characters and/or images constitute variable information (different pieces information) and satisfy the above-mentioned demand.
When looking at an electric-decorating display members, it is required to install an electric-decorating apparatus having a light diffusion layer capable of not only irradiating light onto the members but also performing appropriate light diffusion. In addition, a light diffusion layer may be added to the illuminating display member to enhance attractiveness of images formed on the layer in cooperation with appropriate light transmission assigned to the layer.
Further, various methods of providing the above-mentioned different pieces information, except the ink-jet method, have also been known. Among them, a method called "sublimable thermal transfer method" has occupied the attention. The method, which uses sublimable dyes, produces full color images having excellent continuous gradations and being almost equal to color photographs.
A thermal transfer sheet for the sublimable thermal transfer method is generally provided with a such substrate as a polyester film. On one side surface of the substrate, a dye layer containing of sublimable dyes and a binder are formed, while on its other side surface, a heat-resisting layer is formed for preventing adhesion with the thermal head.
The thermal transfer sheet is put on an image-receiving sheet having a receptor layer, such as a polyester resin, in a manner that the dye surface of the thermal transfer sheet faces the receptor layer. Applying heat to the side of the heat-resisting layer of the thermal transfer sheet by the thermal head according to the shapes of images causes dye in the dye layer to transfer into the receptor layer of the image-receiving sheet, thus forming desired images on the image-receiving sheet.
Based on such sublimable thermal transfer method, Japanese Patent No. 7-77832 discloses one example of the thermal transfer sheets. This exemplified a thermal transfer sheet which having a substrate on which provided are an image-receiving transfer resin layer having dye receptive performance, a thermal transfer layer containing dyes, and a hiding white-color transfer layer for hiding images transferred with the thermal transfer layer. This thermal transfer sheet makes it possible to transfer the image-receiving transfer resin layer on a transparent supporting member, to form transfer images with the thermal transfer layer on the thus transferred image-receiving transfer resin layer, and to additionally transfer the hiding white transfer layer on the images. This provides image-printed materials.
In thus-provided image-printed materials, however,the role of the white transfer layer is to reflect light entering through the transparent supporting member and to raise the density of the transferred images when looked laterally through the transparent supporting member. In other words, the images are produced as being reflection images which do not have appropriate light transmission property and light diffusion property, both of which are necessarily required to electric-decorating display members.
As summaries, there are following drawbacks in the conventionally used electric-decorating display members. When such display members are produced by an offset printing method etc. with the use of pre-formed plates, characters and/or images having only a single piece of information are provided in each printing lot. Hence, there is a drawback that such printing methods cannot satisfy users who desires to have electric-decorating display members on which characters and/or images having different pieces of information are formed in each printing lot, as is required in personal use.
In order to meet such diversification in printed information, there is known an ink jet method. However, this ink jet method also has some drawbacks. That is, water-soluble ink is used for forming images, with the result that image-printed materials are poor in durability including water resistance and scuff resistance, and gradation of images is also poorer than color photographs.
An object of the present invention is to solve the above-mentioned various problems, and to provide image-printed materials handled as electric-decorating display members (i); on which different pieces of information made up of characters and/or images can easily be formed member by member, as is required in personal use, (ii); which have higher durability including water resistance and scuff resistance, (iii); which have an image quality providing a continuous gradation as excellent as in color photographs, and (iv); which look attractively by virtue of appropriate light diffusion and transmission properties, to provide thermal transfer sheets used in producing the image-printed materials, and to provide a recording method of obtaining the image-printed materials.